Measurement probe with heat cycle event counter

ABSTRACT

A measurement device is disclosed, embodiments of which are adapted to withstand, detect, and record detection of heat cycle events, including autoclave cycles. Embodiments of the measurement device comprise a sensor for measuring a characteristic of a medium and a heat cycle detection unit. Embodiments of the heat cycle detection unit comprise a temperature or atmospheric pressure responsive element, a detection module, data interface, and data memory. In one disclosed embodiment, the temperature or pressure responsive element is configured to respond to a characteristic of a heat cycle event while the heat cycle detection unit is off. In another disclosed embodiment, the detection module is configured to automatically power off the heat cycle detection unit in response to detecting an autoclave cycle. Methods of using the devices are also disclosed.

BACKGROUND

1. Field of the Invention

The present invention relates to measurement probes. More particularly,the invention relates to devices and methods used to detect and countheat cycles experienced by measurement probes.

2. Description of the Related Art

Control of industrial processes is largely dependent on measurementsignals received from measurement devices within process mediums.Measurement probes, which are equipped with sensors such as pH sensors,temperature sensors, redox sensors, carbon dioxide sensors, anddissolved oxygen sensors, are frequently used to monitor biological andchemical processes in the fields of biotechnology, pharmaceuticals, andfood/beverage processing. In such industries, accuracy of measurementsis critical.

In such industries, sterilization or cleaning is also critical. Frequentsterilization or cleaning is often required in these industries, becausebacteria and other microorganisms may proliferate on unsterilizedsurfaces and create health risks. Additionally, sterilization orcleaning of measurement probes is needed to prevent contaminationdeposits from building up on the surface of the probes where they canintroduce errors into the measurement signals.

Three sterilization or cleaning methods are frequently employed tosterilize equipment used in biological or chemical processes:steam-in-place sterilization, clean-in-place, and autoclaving.Steam-in-place sterilization procedures allow for in-line pressurizedsteam sterilization of all surfaces located within the interior of areaction vessel or other processing container (herein referred to as aprocessing vessel), thus providing for sterilization withoutdisassembly. Clean-in-place procedures allow for in-line cleaning byflushing the process vessel and associated piping with sanitizingchemical solutions at elevated temperatures. Autoclaving involvessubjecting the processing vessel and the entire probe, to pressurizedsteam heat within a separate autoclave chamber. Autoclaving is often apreferred method of sterilization at least in part when the processingvessel is relatively small and transportable to the autoclave chamber.The major drawback to autoclaving is that the entire probe body issubjected to the high sterilization temperature and this can have adetrimental effect on any internal circuitry that is powered up at thetime. If the probes is externally powered then it must be disconnectedfrom its signal and/or power cable before it is placed in the autoclave.In many industries, subjecting the process vessel, probes, andassociated equipment to high pressure steam at 121° C. in an autoclavefor 20-30 minutes is sufficient to achieve sterilization. However, it isnot uncommon to find that the vessel, probes, and associated equipmentare exposed to pressurized steam at temperatures in excess of 130° C.and for periods of 60 minutes or longer to insure completesterilization.

Measurement probes can experience structural changes, aging, anddecreased functionality and accuracy through exposure to extremeconditions. Particularly, the rapid increase and decrease of temperatureassociated with common steam heat sterilization or hot chemical solutioncleaning methods leads to probe degradation; thus, measurement probesare consumable products which must be replaced regularly. In industry, abalance is required when determining how frequently to replacemeasurement probes. Premature exchange of probes unnecessarily increasescosts, whereas a probe that has reached the end of its life may failduring use. Loss of the probe measurement in mid-process often resultsin loss of process control and the subsequent ruin of an entirebiological or chemical batch, leading to costly waste and delays.Accordingly, it is important for the probe operator to monitor thecondition and evaluate the fitness for service of industrial measurementprobes by tracking the number of heat cycles that it has experienced.

SUMMARY

The present disclosure describes devices and methods used to detect andcount heat cycles experienced by measurement probes, particularly heatcycles associated with steam heat sterilization and hot chemicalsolution cleaning procedures. These procedures are among the greatestcontributors to probe degradation and failure. Accordingly, by providingmeans for detecting and maintaining a count of the heat cyclesassociated with these procedures, the devices and methods describedherein will help probe operators determine the risk associated withcontinued use of the probe and determine when it is time to replace themeasurement probes.

The embodiments disclosed herein each have several innovative aspects,no single one of which is solely responsible for the desirableattributes of the invention. Without limiting the scope, as expressed bythe claims that follow, the more prominent features will be brieflydisclosed here. After considering this discussion, one will understandhow the features of the various embodiments provide several advantagesover current measurement probes.

One aspect of the disclosure is a measurement device adapted towithstand and automatically detect a heat sterilization or cleaningcycle and increment and maintain a counter of the total number of cyclesfor later review by the operator, particularly when the measurementdevice is disconnected from all external power sources. The deviceincludes a measurement probe including a sensor configured to detect acharacteristic of a medium and generate a measurement signal; acondition responsive element including either a temperature responsiveelement or an atmospheric pressure responsive element; and a heat cycledetection unit including a detection module, a data interface, and adata memory. The detection module is configured to detect a heat cycleevent using the condition responsive element, and record detection ofthe heat cycle event in the data memory. In some embodiments the heatcycle event is part of an autoclave procedure, a steam-in-placesterilization procedure, or a clean-in-place procedure. In someembodiments the device is configured to automatically power up the heatcycle detection unit as soon as the heat cycle is detected, the heatcycle detection unit then increments a counter, and then the devicepowers itself off to protect the circuit from prolonged and excessiveheat exposure as in the case of an autoclave procedure where the entireprobe is autoclaved. In some other embodiments the device willautomatically turn itself back on when the heat cycle is complete andthe device has cooled off to a safe operating temperature. In someembodiments, the device will automatically turn itself back on when theheat cycle is complete and the device has cooled off to a safe operatingtemperature, at which point the device records the occurrence of theheat cycle, and then the device automatically powers off until the nextheat cycle is detected. In other embodiments the device will remain offto conserve battery power and only turn itself back on briefly whenanother heat cycle is detected and the cycle needs to be counted by theheat cycle detection unit. In some embodiments, the measurement probeand the heat cycle detection unit are separably connected. In otherembodiments, the measurement probe and the heat cycle detection unit arefixedly integrated.

In some embodiments, the condition responsive element is a first switchconfigured to transition from a first state to a second state when thefirst switch exceeds a first temperature or a first pressure. In suchembodiments, the detection module is configured to record detection of aheat cycle event in the data memory in response to the first switchtransitioning from the first state to the second state. The measurementdevice may further include a capacitor coupled to the first switch,which is configured to discharge in response to the first switchtransitioning from the first state to the second state. In suchembodiments, the detection module need not be powered up during anautoclave cycle but is configured to detect the discharged capacitor andrecord detection of a heat cycle event in the data memory after theautoclave detection unit is powered back on following an autoclavecycle. The first switch changes to its second state at some pre-definedtemperature that marks the beginning of the heat cycle. This secondstate discharges a capacitor. When the detection module powers back upit detects the discharged capacitor and increments the event counter.

In some embodiments, the measurement device also includes a portablepower source in addition to, or instead of, a capacitor. In suchembodiments, the detection module is configured to record detection of aheat cycle event in the data memory in response to a temperatureresponsive element exceeding a first temperature or an atmosphericpressure responsive element exceeding a first pressure. After thecounter is incremented the autoclave detection unit is configured topower off in response to the temperature responsive element exceedingthe first temperature or in response to the atmospheric pressureresponsive element exceeding the first pressure. In some suchembodiments, the measurement device includes a second switch configuredto transition from a power-off state to a power-on state when the secondswitch falls below a power-on temperature or a power-on pressure. Insuch embodiments, the autoclave detection unit is configured toautomatically power on when the second switch transitions from thepower-off state to the power-on state. In some embodiments, the secondswitch and the condition responsive element are one and the same; auniversal switch can acts as both the second switch and the conditionresponsive element.

The first switch and/or the second switch in various embodiments areselected from the group consisting of: a bimetallic strip, an integratedthermal switch, and a pressure switch. The condition responsive elementof other embodiments may be selected from the group consisting of: aresistance temperature detector, a bimetallic strip, an integratedthermal switch, a positive temperature coefficient thermistor, switchingPCT thermistor, or other thermistor, a pressure switch, a piezoelectricpressure sensor, an electromagnetic pressure sensor, a capacitivepressure sensor, and a piezoresistive strain gauge. In variousembodiments, the first temperature and/or power-on temperature arewithin a range of 50 to 120 degrees Celsius, and the first pressureand/or power-on pressure are within a range of 15 to 45 psi.

In some embodiments, the measurement device also includes a couplingelement configured to engage with a vessel body such that, when thecoupling element is engaged with the vessel body, the measurement deviceincludes a distal portion that is positioned within a vessel cavity anda proximal portion that is positioned external to the vessel cavity. Insome such embodiments, the condition responsive element is positioned inor on the distal portion. In other embodiments, the condition responsiveelement is positioned in or on the proximal portion. When the conditionresponsive element is positioned in or on the proximal portion, themeasurement device may additionally include a vessel temperatureresponsive element positioned in or on the distal portion. In suchembodiments, the detection module is configured to detect a heat cycleevent and record detection of the heat cycle event in the data memory inresponse to either the condition responsive element exceeding a firsttemperature or pressure or the vessel temperature responsive elementexceeding a vessel sterilization temperature. Additionally, in suchembodiments, the detection module may be configured to detect anautoclave cycle and record detection of the autoclave cycle in the datamemory in response to the condition responsive element exceeding a firsttemperature or pressure, and the module may be further configured todetect a steam-in-place cycle and record detection of the steam-in-placecycle in the data memory in response to only the vessel temperatureresponsive element exceeding the vessel sterilization temperature. Theautoclave detection unit can be configured to power off when anautoclave cycle is detected and optionally power off when asteam-in-place cycle is detected.

In some embodiments both a condition responsive element and atemperature responsive element are located in the distal end of themeasurement device and another temperature responsive element is locatedin the proximal end of the device. When a preset temperature limit isexceeded in the sterilization or cleaning procedure in the distal end ofthe device, the condition responsive element changes state and powers onthe circuit in the detector module. The module then increments the heatcycle counter and additionally uses the temperature responsive elementin the distal end to measure additional information such as maximum heatexposure and length of exposure time in the case of steam-in-place orclean-in-place procedures. The temperature responsive element in theproximal end is also powered on and it monitors the device temperatureat the proximal end. If the proximal temperature exceeds a preset limitthen the device logic determines that the device is being autoclaved andthe circuit completely shuts down after incrementing the heat cyclecounter.

In some embodiments, the measurement device also includes a pH sensorpositioned in the distal portion. In one such embodiment, a conditionresponsive element in the distal end can change state due to a processheat cycle and switch on the device's power and the detection module canbe configured to differentiate and detect a clean-in-place cycle andrecord detection of the clean-in-place cycle when a distally-locatedtemperature responsive element exceeds a clean-in-place temperature anda measurement from the pH sensor exceeds a clean-in-place pH level, bothwithin a defined period of time. The distally-located temperatureresponsive element of some embodiments is the vessel temperatureresponsive element disclosed above. In at least some embodiments, theclean-in-place temperature is within a range of 65 to 95 degreesCelsius, and the clean-in-place pH is within the extreme ranges ofeither 9 to 14 pH or 1 to 4 pH.

In various embodiments, the first temperature and/or the vesseltemperature are within a range of 50 to 120 degrees Celsius, and thefirst pressure is within a range of 15 to 45 psi. The measurement probeis selected from the group consisting of an amperometric, apotentiometric, an optical, a capacitive, and a conductive probe.Additionally, in some embodiments, the sensor is selected from the groupconsisting of a pH sensor, a temperature sensor, a dissolved oxygensensor, and a combination thereof. The detection module of someembodiments is selected from the group consisting of a circuit, amicroprocessor, a Digital Signal Processor, an Application SpecificIntegrated Circuit, and a Field Programmable Gate Array. The datainterface of some embodiments is selected from the group consisting of awireless transmitter, an input/output terminal, a data bus, acontactless inductive coupling interface (see e.g. DE 19540854A1, DE4344071A1, and U.S. Pat. Nos. 7,785,151, 6,705,898, 6,476,520; each ofwhich is incorporated herein by reference in its entirety and fordisclosure thereof), and an industry standard 8 pin connector. In someembodiments, the measurement device also includes a power-gatheringsystem, such as, for example, a photodiode or a photovoltaic cell.

An additional aspect of the disclosure is a method of automaticallycounting autoclave and other heat sterilization cycles and/or cleaningcycles experienced by any embodiment of the measurement device describedabove, while protecting the circuitry contained within the measurementdevice and managing the device's power supply. The method includesdetecting a heat sterilization cycle using a first temperatureresponsive element that is configured to respond when the temperatureexceeds a first temperature, automatically powering up the detectionunit circuitry if off, recording detection of the heat sterilizationcycle in a data memory and incrementing a counter, and automaticallypowering off the detection unit circuitry after detection of the heatsterilization cycle, if it is desired in a particular process procedureto protect the device's circuit from excessive heat during the heatcycle and to conserve the device's power.

Another aspect of the disclosure is a method of automatically counting aheat cycle experienced by a measurement device. The method includesproviding a measurement device, the device including a measurement probehaving a sensor configured to detect a characteristic of a medium andgenerate a measurement signal, a condition responsive element, and aheat cycle detection unit having a detection module, a data interface,and a data memory. The method further includes detecting a heat cycleevent, using the condition responsive element and recording detection ofthe heat cycle event in the data memory. In some embodiments, the heatcycle event is an autoclave cycle, a steam-in-place sterilization event,or a clean-in-place event. In some embodiments, the device is configuredto automatically power up the heat cycle detection unit after detectionof the heat cycle event and then, after incrementing the counter, powerit down if the heat cycle event comprises an autoclave cycle.

In some embodiments of the method, the condition responsive element is afirst switch that transitions from a first state to a second state whenthe first switch exceeds a first temperature or a first pressure, andthe detection module records detection of a heat cycle event in the datamemory in response to the first switch transitioning from the firststate to the second state. In some such embodiments, the method alsoincludes discharging a capacitor coupled to the first switch in responseto the first switch transitioning from the first state to the secondstate. In such embodiments, detecting a heat cycle event using thecondition responsive element involves detecting a discharged capacitor.In some such embodiments, detecting a discharged capacitor and recordingdetection of a heat cycle event in the data memory occur after theautoclave detection unit is powered on following an autoclave cycle.

In some embodiments of the method, the autoclave detection unit receivespower from a portable power source electrically coupled to themeasurement device. The detection module of some such embodimentsrecords detection of a heat cycle event in the data memory in responseto the condition responsive element exceeding a first temperature or afirst pressure. The autoclave detection unit of some such embodimentspowers off in response to the condition responsive element exceeding thefirst temperature or the first pressure. In some embodiments, the methodadditionally includes automatically powering on the autoclave detectionunit when a second switch in the measurement device transitions from apower-off state to a power-on state. In such embodiments, the secondswitch transitions from the power-off state to the power-on state whenthe second switch falls below a power-on temperature or pressure. Insome embodiments, a universal switch within the measurement deviceincludes both the second switch and the condition responsive element.

In various embodiments of the method, the first temperature and/or thepower-on temperature are within a range of 50 to 120 degrees Celsius,and the first pressure and/or the power-on pressure are within a rangeof 15 to 45 psi.

The method of some embodiments also includes engaging with a vessel bodysuch that a distal portion of the measurement device is positionedwithin a vessel cavity and a proximal portion of the measurement deviceis positioned external to the vessel cavity. In some such embodiments,the condition responsive element is positioned in or on the distalportion. In other embodiments, the condition responsive element ispositioned in or on the proximal portion.

In some embodiments having the condition responsive element positionedin or on the proximal portion, the detection module detects a heat cycleevent and records detection of the heat cycle event in the data memoryin response to either the condition responsive element exceeding a firsttemperature or first pressure or a vessel temperature responsive elementpositioned in or on the distal portion exceeding a vessel sterilizationtemperature. In some such embodiments, the step of detecting a heatcycle event and recording detection of the heat cycle event in the datamemory includes one of: detecting an autoclave cycle and recordingdetection of the autoclave cycle in the data memory in response to thecondition responsive element exceeding a first temperature or a firstpressure, or detecting a steam-in-place cycle and recording detection ofthe steam-in-place cycle in the data memory in response to the vesseltemperature responsive element exceeding the vessel sterilizationtemperature and the condition responsive element not exceeding a firsttemperature or a first pressure. In some such embodiments, the autoclavedetection unit powers off when an autoclave cycle is detected andoptionally powers off when a steam-in-place cycle is detected.

In the method of some embodiments, the detection module detects aclean-in-place cycle and records detection of the clean-in-place cyclewhen: (1) a temperature responsive element located in or on the distalportion exceeds a clean-in-place temperature, and (2) a measurement froma pH sensor positioned in the distal portion exceeds a clean-in-place pHlevel, both within a defined period of time. In some such embodiments,the temperature responsive element located in or on the distal portionis the vessel temperature responsive element.

In some embodiments of the method, the clean-in-place temperature iswithin a range of 65 to 90 degrees Celsius and/or the clean-in-place pHis within a range of either 9 to 14 pH or 1 to 4 pH. Additionally oralternatively, in some embodiments, the first temperature and the vesseltemperature are within a range of 50 to 120 degrees Celsius and thefirst pressure is within a range of 15 to 45 psi.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned aspects, as well as other features, aspects, andadvantages of the present technology will now be described in connectionwith various embodiments, with reference to the accompanying drawings.The illustrated embodiments, however, are merely examples and are notintended to be limiting. Throughout the drawings, similar symbolstypically identify similar components, unless context dictatesotherwise. Note that the relative dimensions of the following figuresmay not be drawn to scale.

FIG. 1 depicts a perspective view of one embodiment of a measurementdevice.

FIG. 2 depicts a block diagram of one embodiment of a measurementdevice.

FIG. 3A depicts a block diagram of another embodiment of a measurementdevice.

FIG. 3B is a flowchart illustrating one method of operations performedby the measurement device of FIG. 3A.

FIG. 4A depicts a block diagram of another embodiment of a measurementdevice.

FIG. 4B is a flowchart illustrating one method of operations performedby the measurement device of FIG. 4A.

FIG. 5A depicts a block diagram of another embodiment of a measurementdevice.

FIG. 5B is a flowchart illustrating one method of operations performedby the measurement device of FIG. 4A.

FIG. 6A depicts a block diagram of another embodiment of a measurementdevice.

FIG. 6B is a flowchart illustrating one method of operations performedby the measurement device of FIG. 5A.

FIG. 7A depicts a block diagram of another embodiment of a measurementdevice.

FIG. 7B is a flowchart illustrating one method of operations performedby the measurement device of FIG. 6A.

FIG. 8 depicts a block diagram of another embodiment of a measurementdevice.

FIG. 9 depicts a block diagram of another embodiment of a measurementdevice.

FIG. 10 depicts a circuit diagram for an embodiment of a heat cycledetection unit.

FIG. 11 depicts a schematic circuit diagram for an embodiment of a heatcycle detection unit.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

In the following detailed description, reference is made to theaccompanying drawings, which form a part of the present disclosure. Theillustrative embodiments described in the detailed description,drawings, and claims are not meant to be limiting. Other embodiments maybe utilized, and other changes may be made, without departing from thespirit or scope of the subject matter presented here. It will be readilyunderstood that the aspects of the present disclosure, as generallydescribed herein, and illustrated in the Figures, can be arranged,substituted, combined, and designed in a wide variety of differentconfigurations, all of which are explicitly contemplated and form partof this disclosure.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the disclosure.It will be understood by those within the art that if a specific numberof a claim element is intended, such intent will be explicitly recitedin the claim, and in the absence of such recitation, no such intent ispresent. For example, as used herein, the singular forms “a”, “an” and“the” are intended to include the plural forms as well, unless thecontext clearly indicates otherwise. As used herein, the term “and/or”includes any and all combinations of one or more of the associatedlisted items. It will be further understood that the terms “comprises,”“comprising,” “includes,” and “including,” when used in thisspecification, specify the presence of stated features, integers, steps,operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, elements, components, and/or groups thereof. Expressionssuch as “at least one of,” when preceding a list of elements, modify theentire list of elements and do not modify the individual elements of thelist.

To assist in the description of the devices and methods describedherein, some relational and directional terms are used. “Connected” and“coupled,” and variations thereof, as used herein include directconnections, such as being contiguously formed with or attached directlyto, on, within, etc. another element, as well as indirect connectionswhere one or more elements are disposed between the connected elements.“Connected” and “coupled” may refer to a permanent or non-permanent(i.e., removable) connection.

“Secured” and variations thereof as used herein include methods by whichan element is directly fastened to another element, such as being glued,screwed or otherwise affixed directly to, on, within, etc. anotherelement, as well as indirect means of attaching two elements togetherwhere one or more elements are disposed between the secured elements.

“Proximal” and “distal” are relational terms used herein to describeposition. For clarity purposes only, in this disclosure, position isviewed from the perspective of an individual operating a measurementdevice positioned partially within a processing vessel. The portion ofthe measurement device located external to the vessel is viewed as beingclosest, and therefore, most proximal to the operator. The portion ofthe device positioned within the container is more distally located.

There is a need for a measurement probe that monitors and quantifies itsown usage and operational fitness in the bioprocess industries. Aleading cause of probe degradation in bioprocess applications is thethermo shock associated with the increase and decrease of temperatureassociated with some heat sterilization procedures that utilizepressurized steam and cleaning procedures that utilize hot sanitizingchemical solutions. A bioprocess industry standard for keeping track ofwear on a measurement probe is the number of these heat cyclesexperienced by the probe. In some applications, probes are exposed to nomore than two to ten heat cycles before being retired. In otherapplications, the count may be higher. The particular number of heatsterilization or cleaning cycles that a probe can withstand varies byprobe manufacturer, sterilization or cleaning method, operatormaintenance, and the environmental conditions within the processingmedium; thus, probe operators familiar with their unique uses andprocesses are best equipped to predict the lifespans of their respectiveprobes. Currently, however, in bioprocess laboratory and productionsettings, it is often easy to lose track of the number of heatsterilization or cleaning cycles experienced by each probe.

Accordingly, there is more than one probe design currently on the marketthat is configured to detect and record steam-in-place sterilizationcycles. However, the design of such probes renders them inoperableduring autoclave cycles. In the current models, the probes must beunplugged and fully powered down before being placed in an autoclavechamber; as a result, they can neither detect nor count autoclavecycles. Without being able to automatically detect and count this widelyused sterilization method, in many bioprocess applications the currentgeneration of sterilization-counting probes provides little benefit overconventional probe designs. In addition, probes are often disconnectedfrom external power sources during steam-in-place cycles to avoiddamaging cables which may come in contact with steam supply pipes or thehot vessel wall. Probes which require an external power source to detectand record steam-in-place cycles will not record the steam-in-placeevent if the operator disconnects the probe cables.

Another existing probe design uses recorded temperature andtime-at-temperature data to self-calculate the length of its remaininglifespan. However, these calculations can provide probe lifespanestimates that are not particularly accurate for the application athand. This can lead the process operator into a false sense of safety ashe reuses a probe that self-predicts that it has plenty of lifespan leftand then the probe fails. Lifespans vary across industries and companiesand are dependent on nearly innumerable factors. Additionally, the costof probe failure, and thus, the willingness to accept risk of probefailure, varies across companies.

Various embodiments disclosed herein may overcome some or all of thedeficiencies mentioned above. The embodiments relate to devices andmethods used to monitor and quantify the usage and operational fitnessof measurement probes by automatically (without user input) countingheat cycle events experienced by said probes, even when disconnectedfrom external power supplies. The measurement devices of variousembodiments are each configured to detect exposure to heat sterilizationor hot chemical cleaning cycles, including autoclave cycles,steam-in-place cycles and/or clean-in-place cycles, and subsequentlymaintain an accurate count of the sterilization or cleaning cyclesexperienced. With such an accurate count, laboratory technicians andother probe operators may be able to easily and efficiently determinewhen it is time to order new probes and/or throw away existing probesbased on their own unique experience with that particular bioprocessapplication. There is currently no commercial probe in the bioprocessindustries that can automatically count and record to memory the numberof autoclave cycles that it has experienced. The preferred embodimentsdisclosed herein provide an accurate count of the heat cycles completelyautomatically and with no operator input or assistance. It is completelyautomated. These preferred devices also improve the accuracy of the heatcycle count for probes undergoing steam-in-place and clean-in-placeprocedures. These devices enable accurate heat cycles counts for probeseven when not connected to associated instrumentation for any heat cycleprocedure.

As shown in FIG. 1, the measurement device 100 of various embodimentsincludes at least a measurement probe 102, a condition responsiveelement 106, and an heat cycle detection unit 108. The measurement probe102 includes a sensor 104 configured to detect a characteristic of amedium and generate an electrical measurement signal, typically ananalog signal. The sensor 104 can be any electrochemical sensor known tothose skilled in the art. For example, in some embodiments, the sensor104 is a pH sensor, a temperature sensor, a dissolved oxygen sensor, ora combination thereof. The measurement probe 102 can be amperometric,potentiometric, optical, capacitive, conductive, or any other suitableprobe type known to those skilled in the art.

In various embodiments, the condition responsive element 106 is in theform of a temperature responsive element or an atmospheric pressureresponsive element. In the simplest embodiments, the conditionresponsive element 106 is a mechanical switch or other element thatundergoes a physical transformation in response to an environmentaltrigger. For example, in some embodiments, the condition responsiveelement 106 is a bimetallic strip (also referred to as a thermostat orthermal switch) or a shape memory alloy, such as, for example,nickel-titanium (Nitinol), which undergoes a physical change in shapewhen the temperature rises above a certain threshold. In someembodiments, the materials are selected and configured such that thephysical change occurs within a temperature range of 50 to 120 degreesCelsius, and more preferably, within a range of 100 to 115 degreesCelsius and any sub-range or value therebetween. For example, thephysical transformation may occur at 50° C., 55° C., 60° C., 65° C., 70°C., 75° C., 80° C., 85° C., 90° C., 91° C., 92° C., 93° C., 94° C., 95°C., 96° C., 97° C., 98° C., 99° C., 100° C., 101° C., 102° C., 103° C.,104° C., 105° C., 106° C., 107° C., 108° C., 109° C., 110° C., 111° C.,112° C., 113° C., 114° C., 115° C., 116° C., 117° C., 118° C., 119° C.,or 120° C.

In other embodiments, the condition responsive element 106 is anintegrated thermal switch or pressure switch, which opens or closes anelectrical contact when a threshold temperature or pressure,respectively, has been reached. The threshold temperature may be withinthe range disclosed above. The threshold pressure may be within a rangeof 10 to 60 psi, and preferably, within a range of 15 to 45 psi. Thethreshold pressure may include any sub-range or value therebetween,including, for example, 15 psi, 16 psi, 17 psi, 18 psi, 19 psi, 20 psi,21 psi, 22 psi, 23 psi, 24 psi, 25 psi, 26 psi, 27 psi, 28 psi, 29 psi,30 psi, 31 psi, 32 psi, 33 psi, 34 psi, 35 psi, 36 psi, 37 psi, 38 psi,39 psi, 40 psi, 41 psi, 42 psi, 43 psi, 44 psi, or 45 psi.

In still other embodiments, the condition responsive element 106 is anelectrical element, such as a resistive element, which produces a changein the electrical signal at least when a threshold value is reached. Insome such embodiments, the threshold value may be any of the thresholdtemperatures and pressures disclosed above. The condition responsiveelement 106 of some embodiments is, for example, a positive temperaturecoefficient thermistor, switching PCT thermistor, or other thermistor, aresistance temperature detector (RTD), a piezoelectric pressure sensor,an electromagnetic pressure sensor, a capacitive pressure sensor, apiezoresistive strain gauge, or any other suitable electrical componentknown to those skilled in the art.

The heat cycle detection unit 108 preferably includes at least adetection module, a data memory, and a data interface 112. In FIG. 1,the detection module and data memory are not individually visible;however, they are preferably printed on stacked circuit cards 110. Thedetection module of some embodiments is a general purpose processor. Inother embodiments, it is a Digital Signal Processor (DSP), anApplication Specific Integrated Circuit (ASIC), a Field ProgrammableGate Array (FPGA) or other programmable logic device, discrete gate ortransistor logic, discrete hardware components, or any combinationthereof designed to perform the functions described herein. A generalpurpose processor may be a microprocessor, but in the alternative, theprocessor may be any processor, controller, microcontroller, or statemachine. A detection module may also be implemented as a combination ofcomputing devices.

The data memory may include Random Access Memory (RAM), flash memory,Read Only Memory (ROM), Electrically Programmable ROM (EPROM),Electrically Erasable Programmable ROM (EEPROM), registers, hard disk, amicro-secure digital (SD) card or other removable disk, or any othersuitable form of storage medium known in the art. The data memory iscoupled to the detection module such that the module can readinformation from, and write information to, the data memory. In some butnot all embodiments, the data memory is integral to the detectionmodule. The detection module and the data memory of some embodimentsreside in an ASIC. In alternative embodiments, the detection module andthe data memory reside as individual discrete components.

Continuing with FIG. 1, the data interface 112 allows for thecommunication of signals and information from the detection module to adata output. In some embodiments, the detection module conditions and/ortransforms electrical signals before they reach the data interface 112.Consequently, the data interface 112 of various embodiments transmitsanalog and/or digital signals. The data interface 112 of someembodiments includes one or more radio frequency transmitters, otherwireless transmitters, couplers, universal serial buses (USB) and/orother data buses. In FIG. 1, the data interface 112 comprises aneight-pin connector configured to physically and electrically couple toan external transmitter and power supply (not shown). In someembodiments, the measurement device 100 includes an output component,such as, for example, a display screen or signal lights, to displayprocessed data to a user. In other embodiments, the measurement device100 transmits the data to an external display screen or other outputdevice via near-field communications, radio frequency signals, Bluetoothsignals, or other wireless signals, or through a physical electricalconnection (e.g., electrical wires, cables, or connector pins) or acontactless inductive coupling interface (see e.g. DE 19540854A1, DE4344071A1, and U.S. Pat. Nos. 7,785,151, 6,705,898, 6,476,520; each ofwhich is incorporated herein by reference in its entirety and fordisclosure thereof). The data output of various embodiments includes,preferably, a count of autoclave cycles and/or total sterilization orcleaning cycles experienced by the device as well as probe serial IDnumber, manufactured date, and other meta data useful to the operator.

In some embodiments, the heat cycle detection unit 108 additionallyincludes a protective housing 114 or other casing that wholly orpartially surrounds at least some of the electronic components of themeasurement device 100. The housing 114 of FIG. 1 is configured towithstand high temperatures, such as, for example, at least temperaturesup to 140 degrees Celsius, and/or from steam and moisture. The housing114 may be further configured to protect the electronic componentsdisposed within the housing from such temperatures and/or moisture. Inthe embodiment of FIG. 1, the housing 114 encases stacked circuit cards110 on which the detection module and the data memory are printed.Additionally, in FIG. 1, the housing 114 includes a plurality of glassor plastic-covered windows 116. The windows are designed to permit theentrance of light into the interior of the housing. In such embodiments,one or more photodiodes or photovoltaic cells (not visible in FIG. 1)are included in the heat cycle detection unit 108 to convert lightenergy into current or voltage. As described in more detail below, thephotodiodes and photovoltaic cells are coupled to batteries and/orcapacitors within the system to help replace leaking current or charge.In some embodiments, the windows 116 are covered by a clear plastic orother suitable transparent material. Other embodiments include nowindows or only one transparent window.

In some embodiments, such as the embodiment depicted in FIG. 1, themeasurement probe 102 and the heat cycle detection unit 108 are fixedlyconnected. In other embodiments, the measurement probe 102 and the heatcycle detection unit 108 are separably coupled. In some suchembodiments, the heat cycle detection unit forms, or is positionedwithin, a removable cap. In other embodiments, the heat cycle detectionunit is positioned within a separate transmitter or dongle.

The measurement device 100 of FIG. 1 further includes a vessel-couplingelement 118. The vessel-coupling element 118 is configured to interactwith, and securely connect to, a receiving port in a processing vessel(not shown). Such receiving ports may be positioned on the side or inthe lid of a processing vessel or in a pipe or channel that is fluidlyconnected to the processing vessel. In FIG. 1, the measurement device100 couples to processing vessels via complementary threading. In otherembodiments, a snap fit or other suitable connection means is used. Onceconnected, a distal portion 120 of the measurement device 100,comprising at least the sensor 104, is positioned within an interior ofthe processing vessel. A proximal portion 122 of the measurement device100, comprising at least the data interface 112, is positioned outsidethe processing vessel.

Many of the steps of a method or algorithm and functions described inconnection with the embodiments disclosed herein may be embodieddirectly in hardware, in a software module executed by a processor, orin a combination of the two. All such embodiments are contemplated andincorporated into use of the term: detection module. If implemented insoftware, the functions may be stored on, or transmitted over as, one ormore instructions or code on a tangible, non-transitorycomputer-readable medium.

The steps the detection module is configured and/or programmed toperform include: detecting a sterilization or cleaning event using thecondition responsive element, recording detection of the sterilizationor cleaning event in the data memory, and automatically powering off theheat cycle detection unit if the heat cycle detection unit is still onand the detected sterilization or cleaning event includes an autoclavecycle. The logic and processes needed to perform these functions aredescribed in more detail below.

In a basic embodiment, such as the embodiment depicted schematically inFIG. 2, the measurement device 200 includes a sensor 204 and a conditionresponsive element 206 positioned within, or coupled to, a measurementprobe 202. The device also includes a heat cycle detection unit 208,which is preferably positioned within a transmitter, dongle, orremovable cap. In some embodiments, the condition responsive element 206is located in the heat cycle detection unit 208, rather than themeasurement probe 202. In some embodiments, the heat cycle detectionunit 208 is physically separable from the measurement probe 202. Theheat cycle detection unit 208 includes a detection module 209, a datamemory 211, and an interface 212. In one method of using the measurementdevice 200 of FIG. 2, the measurement probe 202 is disconnected from theheat cycle detection unit 208 and from any power source prior to beingplaced within an autoclave. Autoclaving is then initiated. The conditionresponsive element 206 deforms or otherwise changes shape in response tothe temperature or pressure in the autoclave increasing to near or abovea certain threshold. The set threshold for a given condition responsiveelement 206 is determined by the materials and configuration of thecondition responsive element 206. The condition responsive element 206may have a range of a few degrees within which it undergoes deformation.In some such embodiments, the condition responsive element 206 is abimetallic strip or a shape memory alloy that deforms in response to anincrease in temperature. In some embodiments, when the conditionresponsive element 206 deforms, it or another movable member in contactwith the condition responsive element 206 mechanically locks into asecond position, remaining in the second position even as thetemperature drops. In one embodiment of the method, after theautoclaving is complete, the measurement probe 202 is removed from theautoclave and connected to the heat cycle detection unit 208. During orupon connection to the measurement probe 202, the heat cycle detectionunit 208 detects the presence of an element locked in a second position.The heat cycle detection unit 208 resets the element, causing theelement to move back to a first position, and the detection module 209stores a sterilization or cleaning cycle (e.g. autoclave cycle) count inthe data memory 211. Although in some embodiments the heat cycledetection unit comprises an atmospheric pressure responsive element, andthus the heat cycle detection unit is responding to atmospheric ratherthan temperature events, those of skill in the art will understand thatthe change in atmospheric pressure within the probe is associated withan autoclave cycle and also signals that a heat cycle has occurred.

FIG. 3A provides a schematic of another measurement device embodiment.In FIG. 3A, the measurement device 300 includes a measurement probe 302having a sensor 304 and a condition responsive element 306. In someembodiments, the condition responsive element 306 is located in the heatcycle detection unit 308, rather than the measurement probe 302. Thesensor 304 is electrically coupled to a measurement interface 305configured to provide probe operators with information about theenvironmental condition being sensed by the measurement probe 302. Thecondition responsive element 306 is electrically connected to a heatcycle detection unit 308, which includes a detection module 309, a datamemory 311, a capacitor 313, and an interface 312. In some embodiments,the interface 312 and interface 305 are the same interface.

A method of operations for the measurement device embodiment of FIG. 3A,is shown in the flowchart of FIG. 3B. When describing the functions ofspecific components, reference numbers from FIG. 3A will be used. Atblock 331, the measurement device 300 is disconnected from an externalpower supply, causing the detection module 309 to power down. Themeasurement device 300 can then be placed in an autoclave chamber andsubjected to the high temperatures and pressures of an autoclave cycle.At block 332, the condition responsive element 306, which is in the formof a mechanical thermal switch or pressure switch, moves or deforms at aset threshold temperature or pressure value, respectively, with the setthreshold value determined by the physical and chemical properties ofthe switch 306. The deformation/movement of the switch 306 closes anelectrical contact within a circuit. As shown at block 333, the closingof the electrical contact within the circuit causes a capacitor orsimilar charge storage unit 313 to drain. In some embodiments, theswitch 306 returns to a first, non-deformed position when thetemperature or pressure falls below the threshold value, which returnsthe circuit to its first state. The capacitor remains drained until themeasurement device 300 is reconnected to a power supply and additionalcurrent flows to the capacitor 313. As shown in block 334, after themeasurement device 300 is reconnected to a power supply, the detectionmodule 309 powers back on and detects the discharged capacitor 313. Inresponse, as shown in block 335, the detection module 309 updates acount of heat cycle events and saves the updated count to the datamemory 311.

An additional embodiment of a measurement device is depictedschematically in FIG. 4A. As in the previous embodiment, the measurementdevice 400 includes a measurement probe 402 having a sensor 404electrically coupled to a measurement interface 405 and a conditionresponsive element 406 electrically coupled to a heat cycle detectionunit 408. In some embodiments, the condition responsive element 406 islocated in the heat cycle detection unit 408, rather than themeasurement probe 402. The heat cycle detection unit 408 includes adetection module 409, a data memory 411, and an interface 412. In thepresent embodiment, the detection module 409 is preferably amicroprocessor programmed to control the heat cycle detection unit 408and programmed to transform analog signals received from the conditionresponsive element 406 to digital signals. The interface 412 ispreferably a wireless transmitter configured to output wireless signals,such as, for example, near-field communication, Bluetooth, Wi-Fi, orradiofrequency signals. The interface 412 of some embodiments includesmultiple wireless transmitters capable of outputting multiple forms ofwireless signals. In some embodiments, the wireless signals are receivedby, and displayed on, a handheld device having a display screen.Additionally or alternatively, the interface 412 of some embodimentsincludes a data bus for wired digital outputs. In some embodiments, theinterface 412 and interface 405 are the same interface.

In FIG. 4A, the capacitor 313 of FIG. 3A has been replaced with abattery 413. In other embodiments, the measurement device includes botha battery and a capacitor. In the depicted embodiment, the battery 413is part of the heat cycle detection unit 408, disposed within a housingunit 414. In other embodiments, the battery 413 is electrically coupledto the detection module 409 but physically separable from the heat cycledetection unit 408. In some embodiments, the battery 413 is readilyaccessible to facilitate battery replacement. In some embodiments, thebattery in FIG. 4A is a rechargeable battery. In other embodiments, adisposable battery is used. The battery 413 functions as a portablepower source, thereby allowing at least some of the electronics withinthe measurement device 400 to remain powered when the device 400 isdisconnected from an external power source. Consequently, the heat cycledetection unit 408 is configured to continue functioning when themeasurement device 400 is placed within an autoclave chamber, orotherwise disconnected from an external power source, e.g. during asteam-in-place cycle. The embodiment of FIG. 4A additionally includes apower-gathering system 415. The power-gathering system 415 can includeany portable element capable of converting energy from light intovoltage or current, such as, for example, a photodiode or a photovoltaiccell. In the embodiment of FIG. 4A, a photodiode 415 is included totrickle charge the battery 413 to help maintain charge in the system.

FIG. 4B provides a flowchart depicting a method of counting exposures tosterilization or cleaning cycles performed by the detection module 409of FIG. 4A. At block 440 the probe is disconnected from the externalpower supply and the internal battery continues to power the device. Atblock 441, the detection module 409, which is electrically coupled tothe condition responsive element 406, receives a modified signal fromthe condition responsive element 406. In the embodiments of FIGS. 4A-4B,the condition responsive element 406 is an electrical resistive element,for example, a thermistor or RTD, which experiences significant changesin resistance with changing temperature. In other embodiments, thecondition responsive element 406 is an atmospheric pressure sensor,which generates a changed signal, for example, due to a change inresistance or inductance, as the surrounding pressure changes. Thedetection module 409 of various embodiments is configured to detectchanges in the received signal. The detection module 409 is alsoprogrammed to determine, using known equations, when the changed signalindicates that a select threshold temperature or pressure has beenreached.

In other embodiments (not shown), the condition responsive element is acondition responsive circuit that includes a thermal or pressure switch.In some such embodiments, when the temperature or pressure rises near orabove a threshold level, the thermal switch or pressure switch changesstate, causing the condition responsive circuit to open. The detectionmodule (which receives power from a battery to which it is connected viaan alternate circuit), detects the cessation of current in the conditionresponsive circuit. In other such embodiments, when the temperature orpressure rises near or above a threshold level, a thermal switch orpressure switch changes state, causing a condition responsive circuit toclose. The detection module (which receives power from a battery towhich it is connected via an alternate circuit), detects the flow ofcurrent in the condition responsive circuit. Through such mechanisms,the detection module, in effect, detects that the threshold temperatureor pressure value has been reached.

As shown at block 442 and 443, when the detection module 409 detectsthat the threshold temperature or pressure has been reached, the countof heat cycle events is updated and saved in the data memory 411. Insome embodiments, the detection module 409 increments a counter andstores the new count within the data memory 411. In other embodiments,the detection module 409 stores the date, and optionally the time, ofheat cycle (e.g. autoclave) detection in the data memory 411.

To protect the circuitry from extreme temperatures and pressures, thedetection module 409 then optionally powers down, as shown at block 444(if the circuitry of the device can operate under hightemperature/pressure, the device need not power down). To better protectthe circuitry, in some embodiments, a threshold temperature or pressureis selected that is lower than the ranges described above. For example,in biotechnology, measurement probes are often used to monitor processesoccurring at a temperature range around 37 degrees Celsius, such as, forexample, 35-40 degrees Celsius. In such industries, measurement devicesmay be selected having a threshold temperature of 60-70 degrees Celsius,for example. It will be appreciated by those having ordinary skill inthe art that any threshold temperature or pressure may be selected forcounting sterilization or cleaning cycles that is above the maximumtemperature or pressure experienced by the measurement device duringnormal (non-sterilization or cleaning) operations.

An additional embodiment of a measurement device is depictedschematically in FIG. 5A. As in the previous embodiment 4A, themeasurement device 500 includes a measurement probe 502 having a sensor504 electrically coupled to a measurement interface 505 and a conditionresponsive element 506 electrically coupled to a heat cycle detectionunit 508. In some embodiments, the condition responsive element 506 islocated in the heat cycle detection unit 508, rather than themeasurement probe 502. The heat cycle detection unit 508 includes adetection module 509, a data memory 511, and an interface 512. In thepresent embodiment, the detection module 509 is preferably amicroprocessor programmed to control the heat cycle detection unit 508.The interface 512 is preferably a wireless transmitter configured tooutput wireless signals, such as, for example, near-field communication,Bluetooth, Wi-Fi, or radiofrequency signals. The interface 512 of someembodiments includes multiple wireless transmitters capable ofoutputting multiple forms of wireless signals. In some embodiments, thewireless signals are received by, and displayed on, a handheld devicehaving a display screen (not shown). Additionally or alternatively, theinterface 512 of some embodiments includes a data bus for wired digitaloutputs. In some embodiments, the interface 512 and interface 505 arethe same interface.

In FIG. 5A, the capacitor 313 of FIG. 3A has been replaced with abattery 513 and a capacitor or similar charge storage element 514. Inthe depicted embodiment, the battery 513 is part of the heat cycledetection unit 508, disposed within a housing unit 515. In otherembodiments, the battery 513 is electrically coupled to the detectionmodule 509 but physically separable from the heat cycle detection unit508. In some embodiments, the battery in 513 is readily accessible tofacilitate battery replacement. In some embodiments the battery in FIG.5A is a rechargeable battery. In other embodiments, a disposable batteryis used. The battery 513 functions as a portable power source, therebyallowing at least some of the electronics within the measurement device500 to power up on its own when the device 500 is disconnected from anexternal power source. Consequently, the heat cycle detection unit 508is configured to power on when the measurement device 500 is placedwithin an autoclave chamber (or otherwise disconnected from and externalpower source) and the condition responsive element 506 changes statewhen it exceeds its threshold limit.

FIG. 5B provides a flowchart depicting a method of counting exposures tosterilization or cleaning cycles performed by the detection module 509of FIG. 5A. At block 550 the device has been disconnected from anexternal power source whereupon the device automatically powers down. Atblock 551, the condition responsive element 506, in this embodiment athermal switch, changes state in response to the temperature risingabove the threshold value. This change in state closes the thermalswitch which in turn supplies internal battery power 513 to thedetection module 509 and the memory 511 and begins charging capacitor514. At block 552 the detection module 509 increments the heat cyclecounter, and saves the new number in memory 511. In block 553 thecapacitor has now completely charged and this causes power to be shutoff to the detection module and memory which in turn saves battery powerand protects the microprocessor in 509 and other components of thedetection unit 508 from operating in the excessive heat of an autoclavecycle. In block 554, heat event ends, the probe's temperature sinks backdown past the threshold value of the thermal switch 506, the switchchanges back to its original open state, the battery is disconnectedfrom the circuit, and the capacitor discharges. As a result of theautomatic actions in block 554 the device is now in a state representedby block 555 where the device is now off, conserving the battery 513,and ready to automatically and autonomously auto-start again when thenext heat cycle begins.

FIG. 6A provides a schematic of another embodiment of a measurementdevice 600 having a battery 613 and a heat cycle detection unit 608. Theheat cycle detection unit 608 includes a detection module 609, a datamemory 611, and an interface 612. As in previous embodiments, themeasurement device 600 also includes a measurement probe 602 with asensor 604 electrically coupled to a measurement interface 605. In otherembodiments, the sensor 604 is electrically coupled to the detectionmodule 609. In such embodiments, the detection module 609 is configuredto amplify the signal received from the sensor 604 and convert it to adigital output. The digital output can then be provided to an outputdevice via the interface 612 in a similar manner as the sterilization orcleaning count data that is transmitted to an output device via theinterface 612. In addition, in some embodiments a capacitor or othercharge storage unit (not shown) is included and functions as describedin FIG. 5.

The measurement device 600 of FIG. 6A also has a vessel coupling device618, which is configured to secure the measurement device 600 to aperimeter wall or lid (i.e., the body) of a processing vessel. Invarious embodiments, the measurement device 600 is secured to the bodyof a processing vessel such that a distal portion 620 of the measurementdevice 600 is disposed within an interior cavity of the vessel and aproximal portion 622 of the measurement device 600 is positioned outsidethe vessel.

In some embodiments, the measurement device includes only one conditionresponsive element. In such embodiments, if the condition responsiveelement is positioned on or within a proximal portion of the measurementdevice, it will not be subjected to, nor respond to, temperature orpressure changes that occur within the processing vessel. Consequently,if a steam-in-place cycle or clean-in-place cycle is run within theprocessing vessel, the condition responsive element will not respond,and the sterilization or cleaning cycle will not be counted. Incontrast, autoclaving requires placement of the entire measurement probewithin an autoclave chamber. Consequently, even condition responsiveelements positioned on or within a proximal portion of the measurementdevice will experience the elevated temperatures and pressures of anautoclave cycle. Thus, when a condition responsive element is onlypositioned within a proximal portion of the measurement device, themeasurement device is tailored to count, specifically, autoclave cycles.

Conversely, if only one condition responsive element is present andpositioned on or within a distal portion of the measurement device, thecondition responsive device will be subjected to any elevatedtemperatures and pressures that occur within the processing vessel aswell as elevated temperatures and pressures that occur while themeasurement device is disposed within an autoclave chamber. In suchembodiments, the measurement device is configured to detect and countmultiple forms of sterilization or cleaning cycles. Each detected cycleis counted and stored in memory as a generic sterilization or cleaningcycle.

In some measurement device embodiments, such as the embodiment of FIG.6A, the measurement device 600 includes both a condition responsiveelement 606 positioned on or within the distal portion 620 and acondition responsive element 607 positioned on or within the proximalportion 622. Such embodiments may be configured to detect and countmultiple forms of heat cycles and distinguish between the various forms.

A method of detecting, distinguishing, and counting various forms ofsterilization or cleaning is provided in the flowchart of FIG. 6B. Asshown in block 660, the detection module 609 receives a modified signalfrom a condition responsive element 606 or 607 as the temperature orpressure rises. From the modifications in the signal, the detectionmodule 609 determines when a threshold temperature or pressure has beenreached, as shown in block 661. In block 662, the detection module 609determines whether the modified signal is being received from theproximal condition responsive element 607. If it is, then the entiremeasurement device 600 is being subjected to an elevated temperatureand/or pressure, and one can conclude that the measurement device 600 isin an autoclave chamber undergoing an autoclave cycle. In such cases,the detection module 609 is programmed to update a count of autoclavecycles (and/or a count of generic sterilization or cleaning cycles) asindicated in block 666, save the updated count in the data memory 611 asindicated in block 667, and optionally power down the detection module609 to protect the electronics in the heat cycle detection unit 608, asindicated in block 668.

If the detection module 609 determines that the modified signal is notbeing received from the proximal condition responsive element 607, (andthus, is instead coming from only the distal condition responsiveelement 606), the detection module 609 is programmed to update a countof steam-in-place cycles (and/or a count of generic sterilization orcleaning cycles) as indicated in block 663, and save the updated countin the data memory 611 as indicated in block 664. The detection module609 may optionally be programmed to power down in response to detectingthe heat cycle, although such programming is not necessary forsteam-in-place cycles when the heat cycle detection unit electronics arelocated outside the processing vessel.

FIG. 7A schematically depicts an embodiment of a measurement device 700configured to detect clean-in-place cycles, along with, preferably,autoclave cycles. The provided measurement device 700 includes a heatcycle detection unit 708 having an interface 712, a data memory 711, adetection module 709, and a battery 713. The measurement device 700 alsoincludes a measurement probe 702 having a pH sensor 704 disposed on orwithin the probe 702. The pH sensor 704 of the current embodiment iselectrically coupled to the heat cycle detection unit 708. In someembodiments, the pH sensor 704 is provided to help detect clean-in-placecycles, and the measurement probe 702 includes one or more other sensorsconfigured to sense a condition of the processing medium. In otherembodiments, the pH sensor 704 serves as both the primary sensor of themeasurement probe 702 and the sensor used during detection ofclean-in-place cycles, and thus may be coupled to an interface (notshown) which is used during normal operation for monitoring pH levels.

In FIG. 7A, a vessel coupling device 718 is permanently or separablyaffixed to an outer portion of the measurement probe 702. A firsttemperature responsive element 706 is positioned on or within a distalportion 720 of the measurement device 700, and a second conditionresponsive element 707 is positioned on or within a proximal portion 722of the measurement device 700.

FIG. 7B depicts one embodiment of a method performed by the measurementdevice of FIG. 7A when counting clean-in-place and other heat cycleevents. The detection module 709 receives signals from the conditionresponsive elements 706 and 707, and the signals change as thetemperature or pressure increases and/or crosses a threshold. As shownin blocks 770 and 771, detection module 709 receives a modified signalfrom a condition responsive unit, and from the signal, determines when athreshold value has been reached. The detection module 709 also performsthe operation in block 772 to determine if the modified signal wasreceived from the proximal condition responsive element 707. If it was,then the detection module 709 follows the autoclave detection protocoldescribed previously. As shown in blocks 773-775, the detection module709 updates a count of autoclave cycles, saves the updated count to thedata memory 711, and optionally powers down (if the circuitry of thedevice can operate under high temperature/pressure, the device need notpower down). If the modified signal was not received from the proximalcondition responsive element 707, (and thus, is instead coming from onlythe distal condition responsive element 706), the detection module 709processes signal inputs from the pH sensor 704. In block 776, the devicedetermines if any measurement reading from the pH sensor 704 exceeds aclean-in-place pH threshold within a defined time period, aclean-in-place detection protocol is performed (blocks 777-778). If nopH reading exceeds the clean-in-place threshold during the defined timeperiod, the steam-in-place detection protocol is performed (block779-780). The clean-in-place protocol, shown in blocks 777 and 778,involves updating a count of clean-in-place cycles and saving theupdated count to the data memory 711. Similarly, the steam-in-placeprotocol, shown in blocks 779 and 780, includes updating a count ofsteam-in-place cycles and saving the updated count to the data memory711. The detection module 709 can further be optionally programmed toshut down in response to detection of a steam-in-place cycle and/or aclean-in-place cycle.

In some embodiments, the clean-in-place threshold is at least 60 degreesCelsius and less than 100 degrees Celsius. Typically, the clean-in-placethreshold is between 65 and 90 degrees Celsius, and it can include anysub-range or individual value within that disclosed range, including 65,70, 75, 80, 85 and 90 degrees Celsius. In some embodiments, the pHthreshold is within the ranges of either 9 to 14 pH or 1 to 4 pH and maybe any sub-range or individual value therebetween. For example, theclean-in-place pH threshold of some embodiments is 9, 10, 11, 12, 13, or14. In some embodiments, the defined period of time is between about 30seconds and about 5 minutes, and includes any sub-range or individualvalue therebetween, including 0.5-4, 0.5-3, 0.5-2, 1-5, 1-4, 1-3, 1-2,2-5, 2-4, and 2-3 minutes. The defined period of time includes both theabout 30 seconds to about 5 minutes preceding thetemperature-threshold-reaching event and the about 30 seconds to about 5minutes following the temperature-threshold-reaching event.

In some embodiments of a measurement device, the measurement device canboth automatically power up (i.e., auto-start) and automatically poweritself off at certain points in a heat sterilization or cleaning, orautoclave cycle. This auto-start feature may advantageously provide formore accurate counting of heat cycles as well as provide better powermanagement of the battery and thus longer shelf life of the probe. Forexample, without an auto-start feature, if multiple successive heatcycles are performed on a measurement device without turning it onbetween cycles, only one cycle will be counted. In some embodiments,that cycle is counted during the cycle, just prior to the measurementdevice shutting down. In other embodiments, a cycle is counted when themeasurement device powers back on, for example, by detecting a drainedcapacitor. By either method it is desirable to have the probeautomatically self-start whenever a heat cycle begins again. Byautomatically powering back on as a cycle starts, the measurement deviceof the current embodiment is ready to detect and count each new cyclethat occurs. By use of a thermal switch as a condition responsiveelement the device can be configured to auto-start each time there is anew heat cycle. Furthermore, since the device can auto-start at thebeginning of the heat cycle, there is no need to keep it on after thecounter is incremented and the device can shut itself off for theremainder of the cycle to conserve the battery and protect themicroprocessor from excessive heat.

Measurement device embodiments that perform the method of FIG. 8 includean integral power supply, such as a battery. In some embodiments, both abattery and a capacitor are included. In some embodiments the power,supply is augmented by a portable power supply such as an attachablebattery. In block 880 the device is in a state of complete power down.The device is disconnected from the external power supply and theinternal battery power is turned off. In block 881 the conditionresponsive element changes state at a pre-determined temperaturethreshold, discharges a capacitor, and switches power on to the device.In block 882 the detection module detects that the capacitor has beendischarged and this signals that a heat cycle has begun. In block 883the count is incremented by 1 in memory and saved. In block 884 thedevice powers off the microprocessor for it to better endure the extremetemperatures of an autoclave cycle and to conserve the internal battery.In block 885 the probe's temperature cools to below the temperaturethreshold of the condition responsive device, the element's statechanges back and the device's capacitor is recharged from the battery.In block 886 the device is once again completely powered down and readyto automatically count the next heat cycle.

Another method performed by some embodiments of a measurement device isprovided in the flowchart of FIG. 9. In the depicted method, themeasurement device can both automatically shut itself off andautomatically turn itself back on (i.e., auto-start) at certain pointsin a heat sterilization or cleaning, e.g., autoclave cycle.

Measurement device embodiments that perform the method of FIG. 9 includea portable power supply, such as a battery. In some embodiments, both abattery and a capacitor are included. In block 990 at least the heatcycle detection portion of the device is powered on. As shown in blocks991-994, the detection module of such measurement devices detects that athreshold temperature or pressure has been reached, updates a count ofheat cycle event (e.g. autoclave), saves the updated count in the datamemory, and optionally powers down (if the circuitry of the device canoperate under high temperature/pressure, the device need not powerdown). In one embodiment, a thermal or pressure switch is used. When athreshold temperature or pressure is reached, the switch physicallydeforms and opens a circuit connecting the switch, capacitor, battery,and detection module. When this occurs, the battery no longer providesvoltage and current to the detection module, and the capacitor or othercharge storage unit begins to drain. The detection module receivescurrent from the draining capacitor long enough to detect the openedswitch and record the occurrence of a heat cycle event (sterilization orcleaning) in the data memory. The detection module powers down as thecurrent wanes. As shown in block 995, when the temperature or pressurefalls below a second threshold value (also referred to as a power-ontemperature or pressure), the switch returns to its first, non-deformedposition, which completes the circuit. Charge and voltage from thebattery are again delivered to the detection module, and the detectionmodule turns back on. In embodiments having one universal switch thatfunctions to both power off and power on the detection module, the firstthreshold value and second threshold value are generally equal. Shapememory materials and bimetallic strips are generally configured todeform and reform to their original shapes at substantially similar orequal temperatures.

In an alternative embodiment, the detection module may perform blocks991-994 in response to receiving a changing signal from an electricalcondition responsive element. From the change in signal, the detectionmodule is configured to calculate/detect that a first threshold valuehas been reached. In such an embodiment, a second condition responsiveelement in the form of a mechanical switch is included in a secondcircuit in the measurement device. The detection module is configured toautomatically power up, as recited in block 995, when the mechanicalswitch changes state and closes an electrical contact in the secondcircuit. This occurs when a second threshold value is reached. In suchembodiments, the first threshold value may be the same or different thanthe second threshold value. In some embodiments, the counter incrementsafter the heat cycle ends, rather than at the start of the heat cycle.

FIG. 10 depicts a circuit diagram of one embodiment of a heat cycledetection unit. This particular embodiment automatically detects andrecords heat cycles according to the embodiment described with referenceto FIG. 5B. FIG. 11 is a schematic of a circuit diagram of oneembodiment of a heat cycle detection unit

The various operations and methods described above may be performed byany suitable means capable of performing the operations, such as varioushardware and/or software component(s), circuits, and/or module(s).Generally, any operations illustrated in the Figures may be performed bycorresponding functional means capable of performing the operations.

Information and signals may be represented using any of a variety ofdifferent technologies and techniques. For example, data, instructions,commands, information, signals, bits, symbols, and chips that may bereferenced throughout the above description may be represented byvoltages, currents, electromagnetic waves, magnetic fields or particles,optical fields or particles, or any combination thereof.

The various illustrative logical blocks, modules, circuits, andalgorithm steps described in connection with the embodiments disclosedherein may be implemented as electronic hardware, computer software, orcombinations of both. To clearly illustrate this interchangeability ofhardware and software, various illustrative components, blocks, modules,circuits, and steps have been described above generally in terms oftheir functionality. Whether such functionality is implemented ashardware or software depends upon the particular application and designconstraints imposed on the overall system. The described functionalitymay be implemented in varying ways for each particular application, butsuch implementation decisions should not be interpreted as causing adeparture from the scope of the embodiments of the invention.

For purposes of summarizing the disclosure, certain aspects, advantagesand features have been described herein. It is to be understood that notnecessarily all such advantages may be achieved in accordance with anyparticular embodiment. Thus, the invention may be embodied or carriedout in a manner that achieves or optimizes one advantage or group ofadvantages as taught herein without necessarily achieving otheradvantages as may be taught or suggested herein.

While this invention has been described in connection with what is arepresently considered to be practical embodiments, it will be appreciatedby those skilled in the art that various modifications and changes maybe made without departing from the scope of the present disclosure. Itwill also be appreciated by those of skill in the art that parts mixedwith one embodiment are interchangeable with other embodiments; one ormore parts from a depicted embodiment can be included with otherdepicted embodiments in any combination. For example, any of the variouscomponents described herein and/or depicted in the Figures may becombined, interchanged or excluded from other embodiments. With respectto the use of substantially any plural and/or singular terms herein,those having skill in the art can translate from the plural to thesingular and/or from the singular to the plural as is appropriate to thecontext and/or application. The various singular/plural permutations maybe expressly set forth herein for sake of clarity. Thus, while thepresent disclosure has described certain exemplary embodiments, it is tobe understood that the invention is not limited to the disclosedembodiments, but, on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the scope ofthe appended claims, and equivalents thereof.

What is claimed is:
 1. A measurement device adapted to withstand andautomatically count a heat sterilization or cleaning cycle, comprising:a measurement probe comprising a sensor configured to detect acharacteristic of a medium and generate a measurement signal; acondition responsive element comprising either a temperature responsiveelement or a pressure responsive element, wherein the conditionresponsive element is a first switch configured to transition from afirst state to a second state when the first switch exceeds a firsttemperature or a first pressure; and a heat cycle detection unitcomprising a detection module, a data interface, and a data memory;wherein the detection module is configured to: detect a heat cycle eventusing the condition responsive element, and record detection of the heatcycle event in the data memory in response to the first switchtransitioning from the first state to the second state.
 2. Themeasurement device of claim 1, wherein the heat cycle event is anautoclave cycle, a steam-in-place sterilization cycle, or aclean-in-place sanitizing cycle.
 3. The measurement device of claim 1,wherein the device is configured to automatically power off the heatcycle detection unit after detection of the heat cycle event.
 4. Themeasurement device of claim 1, wherein the device is configured toautomatically power on the heat cycle detection unit at the beginning ofthe heat cycle event in response to a change of state of the conditionresponsive element.
 5. The measurement device of claim 1, wherein themeasurement probe and the heat cycle detection unit are fixedlyintegrated.
 6. The measurement device of claim 1, further comprising acapacitor coupled to the first switch and configured to discharge inresponse to the first switch transitioning from the first state to thesecond state, wherein the detection module is configured to detect adischarged capacitor and record detection of a heat cycle event in thedata memory.
 7. The measurement device of claim 1, wherein the firstswitch is selected from a group consisting of: a bimetallic strip, anintegrated thermal switch, and a pressure switch.
 8. The measurementdevice of claim 1, wherein the heat cycle detection unit is configuredto power on in response to the condition responsive element reaching afirst temperature or a first pressure threshold.
 9. The measurementdevice of claim 1, further comprising a coupling element configured toengage with a vessel body, wherein the measurement device includes adistal portion that is positioned within a vessel cavity and a proximalportion that is positioned external to the vessel cavity when thecoupling element is engaged with the vessel body.
 10. The measurementdevice of claim 1, wherein the sensor is selected from a groupconsisting of an amperometric, a potentiometric, an optical, acapacitive, and a conductive sensor.
 11. The measurement device of claim1, wherein the sensor is selected from a group consisting of a pHsensor, a temperature sensor, a dissolved oxygen sensor, and acombination thereof.
 12. The measurement device of claim 1, wherein thedetection module is selected from a group consisting of a circuit, amicroprocessor, a Digital Signal Processor, an Application SpecificIntegrated Circuit, and a Field Programmable Gate Array.
 13. Themeasurement device of claim 1, wherein the data interface is selectedfrom a group consisting of a wireless transmitter, an input/outputterminal, a data bus, and an industry standard 8 pin connector.
 14. Amethod of automatically counting a heat cycle experienced by ameasurement device, comprising: providing a measurement devicecomprising: a measurement probe having a sensor configured to detect acharacteristic of a medium and generate a measurement signal, acondition responsive element comprising a first switch that transitionsfrom a first state to a second state when the first switch exceeds afirst temperature or a first pressure, and a heat cycle detection unithaving a detection module, a data interface, and a data memory;detecting a heat cycle event, using the condition responsive element;and recording detection of the heat cycle event in the data memory inresponse to the first switch transitioning from the first state to thesecond state.
 15. The method of claim 14, wherein the heat cycle eventis an autoclave cycle, a steam-in-place sterilization cycle, or aclean-in-place sanitizing cycle.
 16. The method of claim 14, wherein thedevice is configured to automatically power off the heat cycle detectionunit after detection of the heat cycle event.
 17. The method of claim14, wherein the device is configured to automatically power on the heatcycle detection unit at the beginning of the heat cycle event inresponse to a change of state of the condition responsive element. 18.The method of claim 14, further comprising discharging a capacitorcoupled to the first switch in response to the first switchtransitioning from the first state to the second state, whereindetecting a heat cycle event using the condition responsive elementcomprises detecting a discharged capacitor.
 19. The method of claim 14,wherein the detection module records detection of a heat cycle event inthe data memory in response to the condition responsive elementexceeding a first temperature or a first pressure.
 20. The method ofclaim 19, wherein the heat cycle detection unit powers on in response tothe condition responsive element exceeding the first temperature or thefirst pressure.